Air compressor



Oct. 6, 1953 E, w. PATTERSON AIR COMPRESSOR 2 Sheets-Sheet 1 Filed June 25, 1947 INVENTOR.

1953 E. w; PATTERSON 2,654,531

AIR COMPRESSOR n Filed June 25, 1947 2 Sheets-Sheet 2 b p E:

3 piston and valve separated from each other sufiiciently to prevent an oil seal or vacuum lock between the otherwise adjoining flat surfaces of the piston and valve.

An unloader valve and pressure regulator such as that shown in Figures 2 and 6 of my above United States Patent No. 2,293,916, and described and claimed therein, and also shown in Figure 2 of the drawings of this application at I85 is used to control and maintain the pressure in the air balance system of the pumping unit. However, any suitable unloading system may be used in the present invention which is not directed to any particular unloading system.

Other objects and advantages of the invention will be apparent from the following description and claims, the novelty consisting in the features of construction, combination of parts, the unique relations of the members and the relative proportioning, disposition, and operation thereof, all as more completely outlined herein and particularly pointed out in the appended claims.

In the drawings, which form part of the present specification:

Figure 1 is a side elevational view of a pumping unit embodying the present invention;

Fig. 2 is an axial vertical View, partly in elevation, taken through the compressor assembly, in the minimum down-stroke position of the pumping unit;

Fig. 3 is a side elevational view of the compressor of Figure 2, with parts broken away and showing its piston in the minimum up-stroke position of the pumping unit.

Fig. 4 is a view similar to Figure 3 but with the compressor piston at the bottom of the stroke in the maximum down-stroke position of the pumping unit.

Fig. 5 is a view similar to Figure 4 showing the compressor piston at the top of the stroke in the maximum up-stroke position of the pumping unit.

Fig. 6 is atransverse sectional view of the valve taken along the line 6-6 of Figure 2;

Fig. 7 is a vertical, sectional view taken along the line 'l1 of Figure 6 and showing the main compressor valve seated in the lower mouth of the compressor chamber;

Fig. 8 is a vertical sectional view taken through the lubricating head of the compressor assembly and particularly showing the method of lubricating the piston rod;

Fig. 9 is a transverse sectional view taken through the center of the compression chamber looking down on the top of the piston as seen along the line 9-9 of Figure 2;

Fig. 10 is a sectional view showing the raised surfaces for preventing a vacuum, viewed from a position beneath the piston and looking toward the same as indicated by the line lfll8 of Figure 3;

Fig. 11 is a transverse, sectional view taken through the lubricating head of the compressor assembly as seen along the line l 1-! I of Figure 2;

Fig. 12 is a top plan view of the lubricating head of the cylinder as viewed along the line l2--I2 of Figure 3;

Figures 13, 14, 15 and 16 are side elevational views, partly in section, of a modified form of compressor assembly, generally corresponding to Figures 2, 3, 4 and 5 respectively;

Fig. 1'7 is a transverse sectional view through the valve of the modified compressor taken along the line I'!--ll of Figure 13; and

Fig. 18 is a vertical, sectional view taken along the line l8-l8 of Figure 17 and showing the seating of the modified main compressor valve.

As seen particularly in Figure 1, there is provided a pumping unit supported jointly by a generally horizontal base 20, and an identical pair of upwardly extending, parallel, triangular members 22 disposed on opposite sides thereof. The individual members 22 are joined together by suitable bracing to form a vertically mounted Sampson post 24 and a pair of angular struts or supports 26, the latter having their ends secured respectively to the top of the upright 24 and adjacent the horizontal base 25], being affixed at the latter point to vertical brackets 28. The lower end of the Sampson post 24 is in turn attached to a pair of mounting shoes 31} of the base by means of a horizontal pin 32.

The conventional, generally horizontal walking beam 34 is pivotally secured at one end to the top of the Sampson post 24 by means of a fulcrum shaft 36 and carries at its opposite end a horsehead 38 over which the reins 48 of a pump Polish rod are led into a cross-bar 41 to which the polish rod 43 is attached. The base of the unit is located adjacent the Well head in such manner that the horsehead will be located directly thereabove in the conventional manner.

An air reservoir tank 42 is located adjacent the Sampson post and mounted on the base 20. Rotatably journalled in the conventional gear box 44 is a low speed drive shaft 46 to the ends of which is keyed a pair of crank arms 48, one on each side of the gear box. The shaft 46 is operatively connected to a power unit by suitable driving means not shown in detail.

A cylindrical air balance cylinder 50 is pivotal- 1y supported by a universal mounting from a cross head 52 afi'ixed to the underside of the walking beam 34, the balance cylinder being thus adapted to reciprocate vertically along a stationary piston 54 supported within the chamber by a vertically disposed hollow piston rod 56. which is pivotally mounted at its base. The upper end of the hollow piston rod communicates with the cylinder 50 and the lower end of the hollow rod 56 communicates with the air reservoir 42 through the pivotal base 58 and air line 60.

A pair of vertically swinging pitman rods 62 is pivotally secured to the cross-head 52 at its upper end and attached by terminal crank pin bearing housings 64 to the crank arms 48 by means of horizontal crank pins 66 mounted in crank arms 48.

Crank pins 66 are eccentrically mounted in their respective crank arms 48 in the following manner: Crank pins 66 are fixed eccentrically to respective disc members 61 which are mounted in circular apertures 59 near the ends of the respective crank arms 48. Adjustment of the stroke length, and hence of the angle of oscillation of walking beam 34, is accomplished by rotating disc members 61 in circular apertures 69, which alters the longitudinal positioning of crank pins 66 on crank arms 48. After the proper angle of oscillation of walking beam 34 has been achieved by rotation of disc members 61 in circular apertures 69, the disc members 61 are cinched into fixed relationship with crank arms 48 by tightening bolts H which inter-connect the spaced furcations l3 and 15 at the ends of crank arms 48. Furcations I3 and 15 are formed by slits 11 which extend from circular apertures 69 outward to the ends of the respective crank arms 48. Additional clamping me t shown) may also be employed to clamp disc members 6'! in fixed position in their respective circular apertures 69.

My eccentric mounting of crank pins 66 is more fully described in my Patent Number 2,576,76 issued November 27, 1951, for Eccentric Crank Pin Mounting, in which Figure 1 is substantially the same as Figure 1 of the present application.

Fixedly secured to the base adjacent the air reservoir by means of a footing member 68 is an upright compressor unit it having slidably extending from its upper end a piston rod 12 connected to a vertically disposed pair of pitman rods 74 through a cross-head I6, the upper ends of the pitrnan rods being provided in turn with horizontal trunnions l8 transversely disposed in a dependent bracket 8B of the walking beam.

The compressor unit with which the present invention is particularly concerned is shown in more detail in Figure 2 and subsequent figures. It consists of a central chamber 82 within which a piston or plunger 33, provided with piston rings 8c, is reciprocated by means of the piston rod 12 extending upward therefrom and passing outward successively through a bushing 35 and an oil storage housing 8%. The cylindrical oil housing 86 is formed with a central annular wall 88 spaced outward from the traversing piston shaft 5 2 so as to define a well 96 thereabout. An oil reservoir 92 is formed between the well wall 88 and the :outer housing wall 94, being provided with an integral, top cover 96 through which access is had to the oil chamber 92 by means of a plugged opening '98. The central, annular wall 86 extends upward only part way to the top 90 so :as to allow a wick lull to be disposed over its upper edge with opposite ends located in the reservoir 92 and in the well 90 respectively. By this means the required quantity of the necessary lubricant is continuously supplied by capillary action to the piston rod 72 as it passes up and down through the oil reservoir 92. The oil from the reservoir '92 runs down piston rod '52, accur'n-ula'tes on top of compressor piston 83, and provides the sealing and lubrication means for the piston 83 and its adjacent cylinder walls.

The compressor chamber 82 is provided with an inlet line I52 and check valve I04 at its base and a breather vent I06 disposed adjacent the upper end. The compression chamber beneath the piston 53 is in communication with the air reservoir 52 by means of the intermediate exhaust chamber H13, an outlet check valve III), and a "discharge line (not shown) connecting outlet valve I I6 and airreservoir 42.

This outlet valve II'll-is only necessary when an unloader H15 in Figure '2) is included in the system. The purpose of the unloader is to open the inlet valve I34 when the air in the air reservoir reaches the desired predetermined pressure. When the air in the air reservoir falls below the desired pressure the unloader functions to return the inlet valve N34 to normal operation.

.During the time that the inlet valve I04 is held open by the unloader, the piston functions only to draw air in and push it out through the inlet valve H34. In order to perform this idling operation during the time that the air reservoir is up to capacity without causing the piston to continually strike the exhaust valve against the pressure of the air reservoir, it is necessary to bleed the air pressure .from beneath the exhaust valve when this idling operation commences.

This is accomplished in the preferred embodimentof my invention, shown in Figures 2 and 4,

by providing the outlet check valve III) and by reducing the diameter of the part of the piston that is opposite and below the inlet port when the piston is in its lowest position.

By this novel arrangement I have provided a bleeder passage from the bottom of the piston to the inlet port through which air under pressure can escape from the exhaust chamber when the exhaust valve is unseated by contact with piston 83 during the first stroke of the idling operation. This escaping air pressure is free :to pass out through the inlet port and the inlet valve 604 while this inlet valve is held open by the unloader as hereinabove described. This effects bleeding of the pressure under the exhaust valve.

The provision of outlet check valve IIO prevents air under pressure from entering the exhaust chamber from the air reservoir in a reverse manner.

When the air in the reservoir falls below the desired pressure and the unloader returns the inlet valve Hi4 to normal operation, air pressure is returned to the exhaust chamber by the close ing of the inlet valve and the down-stroke of the piston.

The exhaust chamber I08 is somewhat circumferentially enlarged over the compressor cylinder 82 thereabove and has disposed therein an annular compressor discharge valve II2 adapted normally to seat against the internal shoulder H4 formed at the intersection of the two chambers. The lower face of the valve H2 in Figures 2 and 7 is provided with a downwardly extending annular collar I-IB of restricted diameter and from which radiate outward a plurality of vertically directed guide fins IIB having their outer edges disposed in sliding relation with re spect to the inner face of the chamber I 08. 'A centering disk I29] is anixed to the base of the chamber Hi8 and is provided with an upwardly opening central recess I22, of inner diameter corresponding to that of the collar I I6 positioned in axial alignment thereabove, the recess and hollow collar being adapted jointly to seat therebetween an expansion coil spring or helix J24 disposed normally to urge the discharge valve I I2 into seated position against the shoulder I14.

It will be seen that the diameter of the valve H2 is intermediate that of the compression chamber 82 and of the dependent chamber I08 so that upon it being unseated, air will pass unrestricted from the compression chamber into the lower chamber between the vertical guide fins MB. This will take place during the down stroke of the piston, when the pressure of the increasingly compressed air in the chamber 82 becomes sufiicient to overbalance the upward force of the spring I24 and the pressure on its under side. However, upon the piston head reaching the bottom of the chamber it will abut against the valve .I i 2 which is opened by the air. Any remaining force or stroke of the piston rod will serve to further depress the valve'I I2 against the pressure of the helix thus in effect providing a piston chamber of automatically variable length, or in other words a depressible floor .in the chamber.

A discontinuous circle of curved, spacing lugs I25 projects below the bottom surface of the piston 83 so .as to separate it a short distance from the valve H2 when in abutment thereagainst, .in order to avoid formation of a suction connection between the adjacent valve and piston faces.

Thus it will be seen that I have produced a highly effective and automatic or self-compensating compressor unit which obviates in a highly effective manner the difi'iculties previously found in air balance pumping units heretofore employed. Such difficulties being associated with the altered piston displacement occasioned by changing the stroke length of the pumping unit.

A similar result is obtained by the modified construction illustrated in Figures 13 through 18 wherein the discharge valve II'Z-A is provided with an annular extension I26 extending upward into the compressor cylinder with its side walls I28 slightly spaced from the adjacent cylinder wall to permit passage of air therearound. This extension I25 is hollow and provided with an annular, integral fiat, top closure I30 upon which the piston head 83-A is adapted to abut. The piston head 83-A may be reduced in length by an amount generally corresponding to the height of the valve extension I26 so that the general proportions of the compressor assembly need not be altered. The extension I26 is of a reduced diameter so as to permit air to be drawn into the compressor through valve IM-A on the up-stroke of the piston 83-A; also to permit the discharge of air therearound when the exhaust valve is unseated; and also to act as a bleeder passage when the unloader is functioning as set forth hereinabove.

While I have shown and described in some detail a presently preferred embodiment of my compressor assembly it is to be understood that various modifications may be made in the construction and operation thereof within the spirit and scope of the subsequently claimed invention I which is to be construed broadly and limited only by the prior art.

I claim:

1. In an air balanced well pumping unit a walking beam, nected to said walking beam, a crank arm having an adjustable length operatively connected to said walking beam, a source of power for said crank arm, a compressor cylinder, an inlet valve to admit air to the compressor cylinder, a piston member operatively connected to said walking beam and reciprocally mounted in said compressor cylinder, a sealing ring mounted on said piston, an exhaust chamber communicating with and forming a coaxial extension of said compressor cylinder, an exhaust valve member reciprocally mounted in said exhaust chamber so as to alternately open and close the communication between said cylinder and said chamber, said piston member being so fixedly positioned in relation to said walking beam that said sealing ring remains within said compressor cylinder during the entire stroke of said piston for every length of said crank arm, and an air displacement extension having a smaller diameter than the respective diameters of said cylinder and said chamber positioned between said piston member and said exhaust valve member and secured to one of said members and extending from said exhaust chamber into said compressor cylinder during the limit of the maximum compression stroke of said piston.

2. In an air balanced well pumping unit a walking beam, a pumping element pivotally connected to said walking beam, a crank arm havin an adjustable length operatively connected to said walking beam, a source of power for said crank arm, a compressor cylinder, an inlet valve to admit air to the compressor cylinder, a piston operatively connected to said walking beam and reciprocally mounted in said compressor cylinder,

a pumping element pivotally con- 8 a sealing ring mounted on said piston, an exhaust chamber communicating with and forming a coaxial extension of said compressor cylinder, an exhaust valve reciprocally mounted in said exhaust chamber so as to alternately open and close the communication between said cylinder and said chamber, said piston being so fixedly positioned in relation to said walking beam that said sealing ring remains within said compressor cylinder during the entire stroke of said piston for every adjustment of the length of said crank arm, said piston being so positioned that at one end of its minimum stroke length said piston is always close enough to the opposing face of said exhaust valve to develop more than the maximum pressure required for the air balanced system in order to unseat said exhaust valve against the pressure of the air pressure below said exhaust valve, and a displacement extension having a smaller diameter than the respective diameters of said cylinder and said chamber on said piston below said sealing ring which can extend into the exhaust chamber after the exhaust valve has opened on the down-stroke of said piston.

3. In an air balanced well pumping unit, a walking beam, a pumping element pivotally connected to said walking beam, a crank arm having an adjustable length operatively connected to said walking beam, a source of power for said crank arm, a compressor cylinder, an inlet valve to admit air to the compressor cylinder, piston operatively connected to said walking beam and reciprocally mounted in said compressor cylinde a sealing ring mounted on said piston, an exhaust chamber communicating with and forming a coaxial extension of said compressor cylinder, an exhaust valve reciprocally mounted in said exhaust chamber so as to alternately open and close the communication between said cylinder and said chamber, said piston being so fixedly positioned in relation to said walking beam that said sealing ring remains within said compressor cylinder during the entire stroke of said piston for every adjustment of the length of said crank arm, said piston being so positioned that at one end of its minimum stroke length said piston is always close enough to the opposing face of said exhaust valve to develop more than the maximum pressure required for the air balance system in order to unseat said exhaust Valve against the pressure of the air pressure below said exhaust valve, and a displacement extension having a smaller diameter than the respective diameters of said cylinder and said chamber on said exhaust valve extending into the compressor cylinder after the exhaust valve has completely opened on the maximum stroke length of the compressor.

4. In an air balanced well pumping unit a walking beam, a pumping element pivotally connected to said walking beam, a crank arm having an adjustable length operatively connected to said walking beam, a source of power for said crank arm, a compressor cylinder, an inlet valve to admit air to the compressor cylinder, a piston operatively connected to said walking beam and reciprocally mounted in said compressor cylinder, a sealing ring mounted on said piston, an exhaust chamber including a closed end communieating with and forming a coaxial extension of said compressor cylinder, an exhaust valve reciprocally mounted in said exhaust chamber so as to alternately open and close the communication between said cylinder and said chamber, said piston being so fixedly positioned in relation to said walking beam that said piston will not cause the said exhaust valve member to contact the closed end of said exhaust chamber when said crank arm is extended to its maximum length, said piston being so positioned that at one end of its minimum stroke length said piston is always close enough to the opposing face of said exhaust valve to develop more than the maximum pressure required for the air balance system in order to unseat said exhaust valve against the pressure of the air pressure below said exhaust valve, and a displacement extension having a smaller diameter than the respective diameters of said cylinder and said chamber on said piston below said sealing ring which can extend into the exhaust chamber after the exhaust valve has opened on the down-stroke of said piston.

EDGAR W. PATTERSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Dietrich May 28, 1907 Reeve Mar. 3, 1908 Knox Oct. 20, 1925 Aldinger Apr. 7, 1936 Patterson Aug. 25, 1942 FOREIGN PATENTS Country Date Great Britain 1899 France 1920 

